1. Field of the Invention
This invention relates to delay generating devices, and more particularly, to an absolute time delay generating device for correcting time delay.
2. Description of Related Art
Clock generator chip can be considered as the heart of a digital electronic device. For example of a personal computer, each system has one or two clock generators responsible for generating ten or more reference clock signals in order to control and regulate system processing speed, memory access, real-time multimedia, network traffic, and wireless network connection.
In modern days, the usage and development of the clock generators are no longer restricted to computers. In practice, many parts of electronic equipment, engine rooms of telecommunication exchange equipment, home entertainment systems, and digital cameras all require clock reference sources.
However, the clock generator is incapable of independently generating accurate baseband frequency. A set of stable reference signals are required for deriving accurate baseband signals via comparison. The stable reference signal is generated by applying an external voltage to a quarts crystal, which, after receiving the external voltage, would generate a stable oscillation signal immune to the ambient environment, thereby forming a signal generating terminal of the clock generator for stabilizing the reference signal.
However, in the field of IC (integrated circuit) design, ICs have been made toward having miniaturized dimensions. The approach of using the quartz crystal as a signal generating terminal of the clock generator for generating reference signals is restricted by physical features of the quartz crystal, for example, the size of the quartz crystal is unlikely to be further reduced. Hence, the quartz crystal is becoming inappropriate for use with miniaturized ICs.
In a situation of not using external quartz crystal, providing a micro-electromechanical or analog circuit is a common approach to generate reference signals. However, the micro-electromechanical or analog circuit in the field of miniaturized-IC design is likely to be influenced by an ambient PVT (process-voltage-temperature) environment, e.g. process defect, voltage noise or temperature variation, thereby undesirably influencing stability of the reference signals.
Therefore, the problem to be solved in the field of micro oscillator design is to develop an absolute time delay generating device, which does not use an external quartz crystal as a signal generating terminal of a clock generator, and which may overcome drawbacks such as output frequency variation caused by change of an ambient PVT environment.